Listed as a defensive back on the Patriots' roster, McCourty has played both cornerback and safety during his career, and has been named to the Associated Press All-Pro second team at both positions (cornerback in 2010, safety in 2013).

McCourty attended Rutgers University, and played for the Rutgers Scarlet Knights football team beginning in 2005. After redshirting his first season, McCourty appeared in all 13 games as a freshman in 2006 and recorded 38 tackles and two interceptions. In 2007, McCourty and his twin brother Jason McCourty started at cornerback, with Devin compiling 63 tackles, two interceptions, one forced fumble, and three blocked kicks on special teams. He was named an All-Big East Conference academic selection in his first two seasons. McCourty started 13 games at cornerback in his 2008 junior season, picking up 57 tackles, one interception, and a blocked punt. In his final season at Rutgers in 2009, McCourty started 13 games at cornerback, while still also working on special teams units. He had a career-high 80 tackles and also recorded one interception and 10 pass deflections. He also averaged 25.4 yards on kickoff returns and had a 98-yard kickoff return, third-longest in school history. Following the season, he was named to the All-Big East first team.

McCourty graduated from Rutgers with a bachelor's degree in sociology.[3]

McCourty finished his rookie season, having started all 16 games, with 82 tackles, 7 interceptions, 1 sack, 2 forced fumbles and 17 passes defensed. He was named to the 2011 Pro Bowl, and was named a First Team All-Pro by the Sporting News and Second Team All-Pro by The Associated Press. Other than winner Ndamukong Suh, McCourty was the only rookie to earn votes (2 of 50) for AP Defensive Rookie of the Year.

During week 7, on October 21, 2012, McCourty got his first career kickoff return touchdown in a 29-26 overtime win against the New York Jets. McCourty was subsequently named AFC Special Teams Player of the Week, for Week 7. After Aqib Talib was traded to the Patriots, McCourty was permanently converted to safety.[7]

Over the entire season, McCourty played a grand total of 1,329 snaps, including special teams, the most of any defensive player in the NFL, and the third highest total of any NFL player, behind two of his offensive lineman teammates, Ryan Wendell and Nate Solder.[8]

In the aftermath of the 2013 Boston Marathon bombings, McCourty made a pledge to aid recovery efforts with a donation of $100 for every tackle he makes during the 2013 season, and $200 per interception.[9] The pledge follows a similar offer by Patriots wide receiver Danny Amendola ($100 per reception, $200 per dropped pass). McCourty finished the season with 69 tackles and 1 interception

In Week 2 against Minnesota, McCourty had an interception that was returned 60 yards until he was pushed out at the 1-yard line. McCourty also made an interception on Ravens quarterback, Joe Flacco in the AFC Divisonal Playoff game against the Baltimore Ravens.

On March 2, 2015, the New England Patriots decided not to use the franchise tag on him, instead tagging Stephen Gostkowski. However, the Patriots came to an agreement with McCourty on March 8, two days before McCourty reached free agency. McCourty's new contract is for 5 years and $47.5 million.[10] It includes a $15 million signing bonus and $7 million in fully guaranteed salary.[11]